Compressor frequency reduction limit protection method and compressor

Abstract

The present invention discloses a compressor frequency reduction protection method and a compressor. The compressor includes an IPM hardware circuit having a sampling resistor. The frequency reduction protection method includes: periodically collecting temperature parameters and electrical parameters on the sampling resistor; after the compressor operates stably, performing current frequency reduction protection on the compressor according to the electrical parameters; when the current frequency reduction protection is started and the compressor operates normally, performing temperature frequency reduction protection on the compressor according to the temperature parameters; and enabling the unit to output the maximum refrigerating capacity within the set frequency. Compared with the prior art, the present invention has temperature sampling and current sampling functions, can effectively avoid problems such as large resistance values caused by harsh working conditions and a series of problems such as poor heat dissipation and small copper surface coverage due to process problems, and the problem of false alarms caused by the virtual high sampling current of the IPM hardware circuit.

Description

Technical Field

[0001] The present invention relates to a compressor, in particular to a compressor frequency reduction protection method and a compressor. Background Art

[0002] When the condensing unit is operating, when the ambient temperature has not reached the set warehouse temperature, it will increase the frequency. When the unit runs to the maximum frequency, it will limit or reduce the frequency according to the current frequency reduction logic; when the output current exceeds the IPM module protection current value set in the hardware circuit, the unit will report IPM module protection and stop. However, in harsh working conditions or when the on-board temperature is too high due to various reasons, the sampling resistor of the IPM hardware protection circuit will cause the IPM module to falsely report protection because it exceeds the optimal temperature operating range, resulting in the shutdown of the condensing unit and affecting the normal use of the unit and the troubleshooting by professionals.

[0003] Therefore, how to design a compressor frequency reduction protection method and a compressor to avoid the problem of false reporting of the IPM module caused by the change of the sampling resistor value is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0004] In view of the problem in the prior art that the change of the sampling resistor value causes false reporting of the IPM module, the present invention proposes a compressor frequency reduction protection method and a compressor.

[0005] The technical solution of the present invention is to propose a compressor frequency reduction protection method. The compressor includes an IPM hardware circuit with a sampling resistor. The frequency reduction protection method includes:

[0006] Periodically collect the temperature parameter and electrical parameter on the sampling resistor;

[0007] After the compressor runs stably, perform current frequency reduction protection of the compressor according to the electrical parameter;

[0008] When the current frequency reduction protection is started and the compressor is running normally, perform temperature frequency reduction protection of the compressor according to the temperature parameter;

[0009] Keep the unit output the maximum refrigerating capacity within the set frequency.

[0010] Further, performing current frequency reduction protection of the compressor according to the electrical parameter includes:

[0011] Obtain the effective value of the three-phase current of the compressor according to the electrical parameter, and judge whether the effective value of the three-phase current is greater than the current limit value;

[0012] When the effective value of the three-phase current is greater than the current limit value, judge whether the continuous number of times that the effective value of the three-phase current is greater than the current limit value is greater than the first preset number;

[0013] If so, perform frequency limiting processing on the compressor; if not, return to the action of collecting the electrical parameters of the sampling resistor.

[0014] Further, after performing frequency limiting processing on the compressor, it further includes:

[0015] Judge whether the effective value of the three-phase current is greater than the current reduction value;

[0016] When the effective value of the three-phase current is greater than the current reduction value, judge whether the continuous number of times that the effective value of the three-phase current is greater than the current reduction value is greater than the second preset number of times;

[0017] If so, perform frequency reduction processing on the compressor; if not, return to the action of collecting the electrical parameters of the sampling resistor.

[0018] Further, performing temperature limit frequency reduction protection on the compressor according to the temperature parameter includes:

[0019] Judge whether the temperature of the sampling resistor is greater than the frequency limiting temperature point according to the temperature parameter;

[0020] When the temperature of the sampling resistor is greater than the frequency limiting temperature point, judge whether the continuous number of times that the temperature of the sampling resistor is greater than the frequency limiting temperature point is greater than the third preset number of times;

[0021] If so, perform frequency limiting processing on the compressor; if not, return to the action of collecting the temperature parameter of the sampling resistor.

[0022] Further, after performing frequency limiting processing on the compressor, it further includes:

[0023] Judge whether the temperature of the sampling resistor is greater than the frequency reduction temperature point;

[0024] When the temperature of the sampling resistor is greater than the frequency reduction temperature point, judge whether the continuous number of times that the temperature of the sampling resistor is greater than the frequency reduction temperature point is greater than the fourth preset number of times;

[0025] If so, perform frequency reduction processing on the compressor; if not, return to the action of collecting the temperature parameter of the sampling resistor.

[0026] Further, after collecting the temperature parameter and electrical parameter on the sampling resistor, the limit frequency reduction protection method further includes:

[0027] Judge whether the IPM hardware circuit meets the protection trigger condition according to the temperature parameter and electrical parameter;

[0028] If so, trigger the protection action of the compressor to stop the compressor.

[0029] Further, judging whether the IPM hardware circuit meets the protection triggering condition according to the electrical parameters includes:

[0030] Obtaining a three-phase current peak value of the compressor according to the electrical parameters, and determining whether the three-phase current peak value is greater than a current protection value;

[0031] If so, the protection triggering condition is met; if not, the protection triggering condition is not met.

[0032] Further, judging whether the IPM hardware circuit meets the protection triggering condition according to the temperature parameter includes:

[0033] Determine whether the temperature of the sampling resistor is greater than a temperature protection value according to the temperature parameter;

[0034] If so, the protection triggering condition is met; if not, the protection triggering condition is not met.

[0035] Furthermore, the electrical parameters are voltage and current parameters on the sampling resistor, and the temperature parameter is the temperature on the sampling resistor.

[0036] The present invention also proposes a compressor, which adopts the above-mentioned frequency limiting and reducing protection method.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects:

[0038] The present invention has temperature sampling and current sampling functions, which can effectively avoid the problem of increased resistance due to harsh working conditions and a series of process problems such as poor heat dissipation and small copper coverage, and false alarms caused by the IPM hardware circuit sampling current being too high. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 Schematic diagram of the protection triggering conditions of the IPM hardware circuit of the present invention;

[0041] Figure 2 This is a flow chart of triggering the compressor protection action of the present invention;

[0042] Figure 3 This is a flow chart of the current limit derating protection of the present invention;

[0043] Figure 4This is the flowchart of the overall limit and derating protection of the present invention. Detailed implementation manners

[0044] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] Therefore, a feature pointed out in this specification will be used to illustrate one feature of one embodiment of the present invention, rather than implying that each embodiment of the present invention must have the illustrated feature. In addition, it should be noted that this specification describes many features. Although some features may be combined together to show possible system designs, these features can also be used in other combinations not explicitly described. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0046] The principle and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0047] Under harsh working conditions or when the on-board temperature is too high due to various reasons, the sampling resistor of the IPM hardware protection circuit will cause false protection of the IPM module due to exceeding the optimal temperature operating range, resulting in the shutdown of the condensing unit and affecting the normal use of the unit and the troubleshooting by professionals. The idea of the present invention is to perform a temperature limit and derating protection according to the temperature of the sampling resistor after the current limit and derating protection action, so as to avoid the problem that the resistance value of the sampling resistor is too high and causes false protection of the IPM module.

[0048] The compressor limit and derating protection method proposed by the present invention includes:

[0049] Periodically collect the temperature parameters and electrical parameters on the sampling resistor;

[0050] After the compressor runs stably, perform current limit and derating protection on the compressor according to the electrical parameters;

[0051] When the current limit and derating protection is started and the compressor is running normally, perform temperature limit and derating protection on the compressor according to the temperature parameters;

[0052] Keep the unit output the maximum refrigerating capacity within the set frequency.

[0053] Among them, the compressor includes an IPM hardware circuit with a sampling resistor. The temperature parameter collected by the present invention is the temperature parameter on the sampling resistor, and the electrical parameters are the voltage and current parameters on the sampling resistor. The three-phase current output by the compressor can be calculated through the voltage and current parameters. The present invention combines current limit frequency reduction protection and temperature limit frequency reduction protection to avoid the problem of false alarms of the IPM module caused by temperature changes of the sampling resistor.

[0054] When the compressor is not running stably, voltage fluctuations are likely to occur, and such voltage fluctuations are very likely to cause misjudgment. In the present invention, both the current limit frequency reduction protection and the temperature limit frequency reduction protection are executed after the compressor runs stably. Here, the current limit frequency reduction protection is set before the temperature limit frequency reduction protection to avoid the influence on the resistance value of the sampling resistor when the current limit frequency reduction protection acts, thereby causing the temperature limit frequency reduction protection to fail.

[0055] Among them, the current limit frequency reduction protection of the compressor is executed according to the electrical parameters, including:

[0056] Obtain the effective value of the three-phase current of the compressor according to the electrical parameters, and judge whether the effective value of the three-phase current is greater than the current limit value;

[0057] When the effective value of the three-phase current is greater than the current limit value, judge whether the continuous number of times that the effective value of the three-phase current is greater than the current limit value is greater than the first preset number of times;

[0058] If so, perform frequency limiting processing on the compressor; if not, return to the action of collecting the electrical parameters of the sampling resistor.

[0059] Please refer to Figure 3 , and its judgment logic for whether the effective value of the three-phase current is greater than the current limit value I1 is the control logic of the above-mentioned current limit frequency reduction protection. Figure 3 For the sake of easy understanding, in , it is directly judged in the second judgment box whether the effective value of the three-phase current is ≥ the current limit value I2 continuously for multiple times, and its judgment logic is the same as that of judging whether the continuous number of times that the effective value of the three-phase current is greater than the current limit value is greater than the first preset number of times in the above control logic. Only when the effective value of the three-phase current is greater than the current limit value in multiple consecutive samplings will it be judged as yes. On the contrary, as long as the continuous number of times that the effective value of the three-phase current is greater than the current limit value does not reach the first preset number of times, if it is detected that the effective value of the three-phase current is less than the current limit value, the counter will be cleared and the detection will start again.

[0060] The determination of the multiple consecutive sampling actions is for preventing logical misjudgment caused by some small spikes when the compressor is interfered. Here, the first preset number of times is set as the threshold N1. Only when the effective value of the three-phase current is greater than the current limit value in N1 consecutive sampling points will the frequency limiting control be triggered.

[0061] Among them, the action of frequency limit control is to limit the increase of the compressor frequency and last for a time t1. However, for the case where the operating frequency of the compressor itself is relatively high, even if the compressor frequency is limited, the problem of excessive current will still occur. To address this, after the frequency limit processing of the compressor, the present invention further includes:

[0062] Judge whether the effective value of the three-phase current is greater than the current reduction value;

[0063] When the effective value of the three-phase current is greater than the current reduction value, judge whether the continuous number of times that the effective value of the three-phase current is greater than the current reduction value is greater than the second preset number of times;

[0064] If so, perform frequency reduction processing on the compressor; if not, return to the action of collecting the electrical parameters of the sampling resistor.

[0065] This part of the action is used to further judge the operating frequency of the compressor. If the effective value of the three-phase current is greater than the current reduction value, it indicates that the three-phase current is too large at this time, that is, the operating frequency of the compressor is too high. At this time, the current cannot be suppressed through frequency limit control, and frequency reduction processing needs to be performed on the compressor. Please refer to Figure 3 , the judgment that the effective value of its three-phase current ≥ the current reduction value I2 is the judgment logic of the rising and falling frequency control. The purpose of the multiple samplings here is the same as that in the frequency limit control, which is also used to avoid misjudgment caused by some small peak currents during the operation of the compressor. It will only be triggered when the effective value of the three-phase current is greater than the current limit value I2 at the second preset number of consecutive sampling points. If it is detected that the effective value of the three-phase current is less than the current limit value I2 at any time during this period, the counter will be cleared and re-detected. Here, the second preset number of times is set the same as the first preset number of times, both are N1 times.

[0066] To avoid misjudgment caused by the temperature of the sampling resistor, the present invention also needs to control the temperature of the sampling resistor in real time during sampling, which is achieved by performing corresponding temperature limit and frequency reduction protection according to the temperature parameter. Specifically

[0067] Perform temperature limit and frequency reduction protection of the compressor according to the temperature parameter, including:

[0068] Judge whether the temperature of the sampling resistor is greater than the frequency limit temperature point according to the temperature parameter;

[0069] When the temperature of the sampling resistor is greater than the frequency limit temperature point, judge whether the continuous number of times that the temperature of the sampling resistor is greater than the frequency limit temperature point is greater than the third preset number of times;

[0070] If so, perform frequency limit processing on the compressor; if not, return to the action of collecting the temperature parameter of the sampling resistor.

[0071] Please refer to Figure 4, the temperature limit frequency reduction protection is triggered after the current limit frequency reduction protection, and is only triggered when it is determined in the current limit frequency reduction protection that the compressor is normal and there is no need to perform frequency reduction or frequency limit action. It is used to eliminate misjudgment caused by the temperature of the sampling resistor. If it is determined in the current limit frequency reduction protection that the compressor is abnormal and frequency reduction or frequency limit action is required, the current limit frequency reduction protection is preferentially executed. The judgment of whether the temperature of the sampling resistor is continuously sampled multiple times ≥ the frequency limit temperature point T1 is the judgment logic of the above frequency limit control action. Here, the temperature of the sampling resistor is sampled multiple times, which is also used to prevent some spikes caused by system interference from resulting in logical misjudgment. Its specific logic is the same as that of the previous current limit frequency reduction protection action. Only when the number of consecutive sampling points where the temperature of the sampling resistor is greater than the frequency limit temperature point T1 reaches the third preset number of times, the frequency limit protection will be triggered. If the temperature of the sampling resistor is less than the frequency limit temperature point T1 once in the middle, the counter will be cleared and re-sampled. Here, the third preset number of times is set to N2. Its action on the compressor frequency limit protection is to limit the frequency increase of the compressor and last for a duration t3.

[0072] For the situation where the temperature of the sampling resistor is too high, it is no longer possible to reduce the temperature of the sampling resistor only by restricting the frequency increase of the compressor. It is necessary to perform frequency reduction on the compressor. Therefore, after the frequency limit processing of the compressor, it also includes:

[0073] Judge whether the temperature of the sampling resistor is greater than the frequency reduction temperature point;

[0074] When the temperature of the sampling resistor is greater than the frequency reduction temperature point, judge whether the number of consecutive times the temperature of the sampling resistor is greater than the frequency reduction temperature point is greater than the fourth preset number of times;

[0075] If so, perform frequency reduction on the compressor. If not, return to the acquisition action of the temperature parameter of the sampling resistor.

[0076] Its Figure 4 The judgment of whether the temperature T of the sampling resistor is ≥ the frequency reduction temperature point T2 is the judgment logic of the above frequency reduction action. Here, multiple samplings are also performed to avoid misjudgment. The fourth preset number of times is set the same as the third preset number of times, both are N2. Its action of frequency reduction processing is to reduce the operating frequency of the compressor and last for a duration t4.

[0077] In addition, during the operation of the compressor, there will also be a problem that the current is too high and damages the circuit. To avoid this situation, in the present invention, when the unit starts, the temperature parameters and electrical parameters are detected, and at any time, when it is found that the temperature parameters or electrical parameters are too high, power-off protection is performed. Specifically

[0078] After collecting the temperature parameter and electrical parameter on the sampling resistor, the limit frequency reduction protection method also includes:

[0079] Judge whether the compressor meets the protection trigger condition according to the temperature parameter and the electrical parameter;

[0080] If so, trigger the protection action of the compressor to stop the compressor.

[0081] Please refer to Figure 1 and Figure 2 , judge whether the compressor meets the protection trigger condition according to the electrical parameter, including:

[0082] Obtain the peak value of the three-phase current of the compressor according to the electrical parameter, and judge whether the peak value of the three-phase current is greater than the current protection value;

[0083] If so, it meets the protection trigger condition, if not, it does not meet the protection trigger condition.

[0084] Please refer to Figure 2 , judge whether the compressor meets the protection trigger condition according to the temperature parameter, including:

[0085] Judge whether the temperature on the sampling resistor is greater than the temperature protection value according to the temperature parameter;

[0086] If so, it meets the protection trigger condition, if not, it does not meet the protection trigger condition.

[0087] Among them, when it is determined that the compressor meets the protection trigger condition, the FO pin of the IPM protection module is set to low level, reporting IPM protection and the unit stops.

[0088] The overall working process of the present invention is described below:

[0089] When the condensing unit starts to operate, the MCU samples the output current and the temperature of the sampling resistor. When the unit operates stably, the current limit and frequency reduction logic is executed. Judge whether the effective value of the three-phase current I meets the condition (I≥I1), I1 is the current limit value. If the effective value of the three-phase current meets the condition (I≥I1) and meets this condition continuously for multiple times, the compressor enters the frequency limit state, restricting the compressor frequency from rising, and this state lasts for t1 seconds; when the system enters the frequency limit state due to current, but due to a series of factors such as working conditions, the current is still rising, judge whether the effective value of the three-phase current meets the condition (I≥I2), I2 is the current reduction value. If the effective value of the three-phase current meets the condition (I≥I2) and meets this condition continuously for multiple times, the compressor enters the frequency reduction state, reducing the compressor frequency, and this state lasts for t2 seconds; in any case, when the peak value of the three-phase current detected by the MCU meets the condition (I≥I3), I3 is the current protection value of the IPM module, immediately trigger the IPM module protection and the unit stops; if it does not meet the condition (I≥I3), the unit operates normally at a certain frequency. Note: I1<I2<I3.

[0090] When the unit does not trigger current-limited frequency reduction, that is, when the unit outputs at the maximum frequency, the temperature-limited frequency reduction logic is executed. It is judged whether the temperature T of the sampling resistor satisfies the condition (T≥T1), where T1 is the temperature-limited frequency value. If the temperature of the sampling resistor satisfies the condition (T≥T1) and continuously satisfies this condition for multiple times, the compressor enters the frequency-limited state, restricting the increase of the compressor frequency, and this state lasts for t3 seconds; when the system enters the frequency-limited state due to the temperature of the sampling resistor, but due to a series of factors such as working conditions, the temperature of the sampling resistor is still rising, it is judged whether the temperature T of the sampling resistor satisfies the condition (T≥T2), where T2 is the temperature-reducing frequency value. If the temperature of the sampling resistor satisfies the condition (T≥T2) and continuously satisfies this condition for multiple times, the compressor enters the frequency-reducing state, reducing the compressor frequency, and this state lasts for t4 seconds; finally, the unit will maintain a certain frequency to output the maximum cooling capacity, and at the same time, the peak value of the three-phase current is monitored in real time, and when the peak value reaches the IPM current protection value, the IPM module protection is reported. Note: The sampling resistor is a metal resistor. If the upper limit value of the optimal operating temperature range of the resistor given by the manufacturer is T3, then T1<T2<T3, and there should be a margin between the temperature-limited frequency reduction points, which is determined according to the actual situation.

[0091] Compared with the prior art, the present invention can add a component temperature detection mechanism to the original current detection mechanism to form a new compressor frequency-limited and frequency-reducing mechanism. During the operation of the unit, the temperature of the key sampling resistor in the IPM hardware circuit is monitored in real time. This logic can effectively avoid problems such as large resistance values caused by poor working conditions and a series of problems such as poor heat dissipation and small copper-clad area due to process problems, and the sampled current of the IPM module is falsely high until it exceeds the current threshold initially set by the IPM module, resulting in false reporting of IPM module protection and shutdown of the condensing unit. When the unit is frequency-limited and frequency-reduced, the on-board temperature and the temperature of the sampling resistor can be effectively controlled.

[0092] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Compressor frequency reduction protection method, the compressor includes an IPM hardware circuit with a sampling resistor, characterized in that, The frequency reduction protection method includes: Periodically collect the temperature parameters and electrical parameters on the sampling resistor; After the compressor runs stably, perform current frequency reduction protection on the compressor according to the electrical parameters; When the current frequency reduction protection is started and the compressor is running normally, perform temperature frequency reduction protection on the compressor according to the temperature parameters; Keep the unit outputting the maximum cooling capacity within the set frequency; Performing current frequency reduction protection on the compressor according to the electrical parameters includes: Obtain the effective values of the three-phase currents of the compressor according to the electrical parameters, and judge the three-phase currents Whether the effective value is greater than the current limit value; When the effective value of the three-phase current is greater than the current limit value, judge whether the continuous number of times that the effective value of the three-phase current is greater than the current limit value is greater than the first preset number of times; If so, perform frequency limiting processing on the compressor, if not, return to the action of collecting the electrical parameters of the sampling resistor.

2. The frequency reduction protection method according to claim 1, wherein After performing frequency limiting processing on the compressor, it further includes: Judge whether the effective value of the three-phase current is greater than the current reduction value; When the effective value of the three-phase current is greater than the current reduction value, judge whether the continuous number of times that the effective value of the three-phase current is greater than the Current reduction value is greater than the second preset number of times; If so, perform frequency reduction processing on the compressor, if not, return to the action of collecting the electrical parameters of the sampling resistor.

3. The frequency reduction protection method according to claim 1, characterized in that Performing temperature frequency reduction protection on the compressor according to the temperature parameters includes: Judge whether the temperature of the sampling resistor is greater than the frequency limiting temperature point according to the temperature parameters; When the temperature of the sampling resistor is greater than the frequency limiting temperature point, judge whether the continuous number of times that the temperature of the sampling resistor is greater than the frequency limiting temperature point is greater than the third preset number of times; If so, perform frequency limiting processing on the compressor, if not, return to the action of collecting the temperature parameters of the sampling resistor.

4. The frequency reduction protection method according to claim 3, characterized in that After performing frequency limiting processing on the compressor, it further includes: Judge whether the temperature of the sampling resistor is greater than the frequency reduction temperature point; When the temperature of the sampling resistor is greater than the frequency reduction temperature point, judge whether the continuous number of times that the temperature of the sampling resistor is greater than the frequency reduction temperature point is greater than the fourth preset number of times; If so, perform frequency reduction processing on the compressor, if not, return to the action of collecting the temperature parameters of the sampling resistor.

5. The frequency reduction protection method according to claim 1, characterized in that After collecting the temperature parameters and electrical parameters on the sampling resistor, the frequency reduction protection method further includes: Judge whether the IPM hardware circuit meets the protection trigger condition according to the temperature parameters and electrical parameters; If so, trigger the protection action of the compressor to stop the compressor.

6. The frequency reduction protection method according to claim 5, characterized in that, Judging whether the IPM hardware circuit meets the protection trigger condition according to the electrical parameters includes: Obtain the peak values of the three-phase currents of the compressor according to the electrical parameters, and judge the three-phase current peak Whether the value is greater than the current protection value; If so, the protection trigger condition is met, if not, the protection trigger condition is not met.

7. The frequency reduction protection method according to claim 5, wherein Judging whether the IPM hardware circuit meets the protection trigger condition according to the temperature parameters includes: Judge whether the temperature on the sampling resistor is greater than the temperature protection value according to the temperature parameters; If so, the protection trigger condition is met, if not, the protection trigger condition is not met.

8. The frequency reduction protection method according to claim 1, wherein The electrical parameters are The voltage and current parameters on the sampling resistor, and the temperature parameter is the temperature on the sampling resistor.

9. Compressor, characterized in that, The compressor adopts the limited frequency reduction protection method described in any one of claims 1 to 8.

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