Method for controlling uniform heating of switch device of switch power source

[0017] Embodiment 1: The purpose of this embodiment is to overcome the problem of uneven heating of each switching tube in a switching power supply including switching tubes, and to provide a method for controlling uniform heating of switching power supply switching tubes. The switching power supply includes a full-bridge converter, The structure of the full-bridge converter is figure 1 As shown, the four switching devices Q1 (first switching device), Q2 (second switching device), Q3 (third switching device), and Q4 (fourth switching device) in the full-bridge converter are all switching devices. , The switching device sequence (that is, the turn-on or turn-off sequence) of each switching device in the full-bridge converter is cycle alternately, that is, the switching device as the leading arm and the switching device as the lagging arm are cycled alternately, The alternating period Tp is twice the switching control period Ts of each switching device; that is, one alternating period Tp includes two switching control periods Ts, among which, for example, Q1 and Q1 in the first switching control period Ts in an alternating period Tp Q2 constitutes the lagging arm, Q3 and Q4 constitute the leading arm, and in the second switching control period Ts in the same alternating period Tp, Q1 and Q2 constitute the leading arm, and Q3 and Q4 constitute the lagging arm.

[0018] Such as image 3 As shown, t0~t12 is an alternating period Tp, in which the time period t0~t6 is a switch control period Ts, and the time period t6~t12 is another switch control period Ts; among them, in the time period t0~t6 (ie During the first switching control period Ts), Q1 and Q2 are 180° turn-on complement each other. When Q3 and Q4 turn off, the current is the largest, which is hard turn-off; Q1 and Q2 lag behind Q3 and Q4 turn-off, and the current is turned off Is 0, soft turn-off (such as image 3 , Q4 is turned off at t1, and Q1 is turned off until t3; on the contrary, in the time period from t6 to t12 (that is, during the second switching control period Ts), Q3 and Q4 are turned on at 180° each other Complementary, when Q1 and Q2 turn off, the current is the largest, which is hard turn-off. Q3 and Q4 lag behind Q1 and Q2 turn off. When turned off, the current is 0, which is soft turn-off (such as image 3 , Q1 turns off at t7, and Q4 turns off until t9).

[0019] After t12, the turn-off sequence of the four switching devices Q1, Q2, Q3, and Q4 repeats the above process. From a long-term perspective, the bridge arm composed of the switching devices Q1 and Q2 is turned off first during half of the working time, which is a hard turn-off After the bridge arm composed of Q3 and Q4 is turned off, it is soft turn-off; while the bridge arm composed of switching devices Q3 and Q4 is turned off first for the other half of the working time, and the bridge arm composed of Q1 and Q2 is turned off afterwards. Soft shutdown. In this way, within a certain working time, the states of the switching devices of the switching tubes constituting the four switching devices are consistent, and the heat generation and switching stress are the same.

[0020] Example 2: Such as Figure 4 As shown, each switching device in the full-bridge converter is composed of two or more switching tubes in parallel, and the control pulses of the two or more switching tubes constituting each switching device are the same. That is, the switching tubes Q11~Q1n are connected in parallel to receive the same switching tube control pulse; Q21~Q2n are connected in parallel to receive the same switching tube control pulse; Q31~Q3n are connected in parallel to receive the same switching tube control pulse; Q41~Q4n are connected in parallel to receive the same switching tube control pulse. Switch tube control pulse; four groups of pulse signals can be pressed image 3 The control pulse generation method shown can realize parallel IGBTs.

[0021] Embodiment 3: This embodiment provides a method for controlling uniform heat generation of a switching power supply switch tube. The switching power supply includes a full-bridge converter. The structure of the full-bridge converter is as follows figure 1 As shown, the four switching devices Q1 (first switching device), Q2 (second switching device), Q3 (third switching device), and Q4 (fourth switching device) in the full-bridge converter are all switching devices. In the full-bridge converter, the switching device as the leading arm and the switching device as the lagging arm alternate in cycles, and the alternating period Tp is 6 times the switching control period Ts of each switching element; that is, one alternating period Tp contains 6 switching control periods Ts. For example, in the first three switching control periods Ts in an alternating period Tp, Q1 and Q2 constitute a lagging arm, and Q3 and Q4 constitute a leading arm, then in the same alternate period Tp, the latter In the three switch control periods Ts, Q1 and Q2 constitute a leading arm, and Q3 and Q4 constitute a lagging arm.