Motor Drive Control for Battery Heating During Vehicle Stop
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Solution Overview
Problem
Existing drive devices for rotating electric machines are unable to raise the temperature of a storage battery when the vehicle is stopped, as the infinite unit cycle of the electrical angle prevents effective power conversion efficiency reduction for heating.
Innovation Solution
A drive device with a control unit that sets the switching signal for the power conversion unit to differ from the normal drive state, allowing for increased discharge and temperature rise of the storage battery even when the rotating electric machine is not rotated, by independent frequency settings for the converter and inverter switching signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the frequency of the switching signal is controlled based on the number of pulses per unit cycle of the electrical angle, then the power conversion efficiency can be reduced to raise the storage battery temperature during vehicle operation, but the storage battery temperature cannot be raised when the vehicle is stopped because the unit cycle becomes infinite
Solution Approach 1:
The patent segments the control of switching signal frequency into two independent parts: (1) converter switching signal frequency controlled by discharge amount, and (2) inverter switching signal frequency controlled by power conversion efficiency. This segmentation allows each frequency to be optimized independently, enabling temperature control during vehicle stop without being constrained by the electrical angle cycle
Solution Approach 2:
The patent introduces dynamic control where the converter switching signal frequency is adjusted based on the discharge amount rather than being fixed relative to the electrical angle cycle. This dynamic adjustment allows the system to operate effectively even when the vehicle is stopped and the electrical angle cycle is infinite
2Temperature
If the power conversion efficiency is reduced to increase discharge amount and raise storage battery temperature, then the temperature control function is achieved, but the system becomes unable to operate when the rotating electric machine is not rotated
Solution Approach 1:
The patent separates the control functions into independent converter and inverter switching signal frequencies, allowing the converter frequency to be controlled by discharge amount independently of the inverter frequency that depends on rotation speed. This enables temperature control function to operate even when rotation speed is zero
Solution Approach 2:
The patent changes the control parameter for converter switching signal from electrical angle-based (which requires rotation) to discharge amount-based (which works at any rotation state). This parameter change allows the system to maintain temperature control capability during vehicle stop when rotation is absent
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the temperature of the storage battery to be raised effectively even when the rotating electric machine is not in operation, facilitating charging by increasing the discharge amount and power loss, thus overcoming the limitations of existing technologies.
Implementation Method 1
a power conversion unit (7b) that converts DC power supplied from the storage battery (4) into AC power, and supplies the AC power to the rotating electric machine (2)
Implementation Method 2
when a temperature of the storage battery is lower than a temperature suitable for charging, the temperature of the storage battery is required to be raised up to the temperature suitable for charging by discharging the storage battery
Data Source
AI summary
Provided is a drive device for a rotating electric machine, including: a power conversion unit configured to convert DC power supplied from a storage battery into AC power, and to supply the AC power to a rotating electric machine; and a control unit output a switching signal to the power conversion unit. The control unit is configured to set, when the storage battery is to be charged, in a case in which a temperature of the storage battery input from an outside is lower than a set temperature suitable for charging, the switching signal for the power conversion unit so as to be different from the switching signal in a normal drive state of the rotating electric machine.